1. Field of the Invention
This invention is in the field of apparatus and methods for indexing magazines retaining molded leadframes and, more particularly, is an apparatus and method for laterally indexing such magazines and for vertically indexing the molded leadframes therein.
2. Description of the Related Art
A series of magazines is normally used to retain large numbers of molded leadframes until they are picked up by an apparatus for handling molded leadframes. Typically, such handling apparatus will pick up a molded leadframe from some point in a working space (i.e. the top of a stack of molded leadframes in a magazine) and deliver it to the top of a stack of molded leadframes in another magazine, or to a different location in which an operation is to be performed on the molded leadframe. Oftentimes, the point in space were the molded leadframe is picked up by the handling apparatus remains constant. In other words, each time that the handling apparatus goes to pick up a molded leadtrame from a magazine, it goes to the same position. Given this, when a molded leadframe is removed from the top of a stack of molded leadframes in a magazine, it is necessary that the stack be indexed upward by a dimension approximately equal to the thickness of one of the molded leadframes. In this manner, the handling apparatus can return each time to the same position in order to pick up the next molded leadframe off of the top of the stack.
The present invention provides a structure and a method for vertically indexing a stack of molded leadframes located in a magazine. In particular, after the top molded leadframe is removed from the stack by a molded leadframe handling apparatus, the vertical indexing structure moves the stack of molded leadframes in the magazine upward by a dimension approximately equal to the thickness of one of the molded leadframes. Note, that the vertical indexing structure can also be used to move a stack of molded leadframes in a magazine downward by a dimension approximately equal to the thickness of one of the molded leadframes. This later action would be required after a molded leadframe was dropped off by the molded leadframe handling apparatus onto the stack of molded leadframes in a magazine, and before the handling apparatus dropped off another molded leadframe onto the top of the same stack. This vertical indexing up or down of a stack of molded leadframes in a magazine permits the molded leadframe handling apparatus to pick up or to drop off, respectively, at the same relative position in a given magazine.
Whether molded leadframe handling apparatus are used to pick up or to drop off a molded leadframe at a specific magazine, if one has a number of such magazines arranged serially, it is necessary that there be sufficient space adjacent to the subject magazine so that the vertical indexing structure can access the molded leadframes therein. This equates to being able to move each magazine in a line of magazines into the desired operation position, one at a time, while leaving enough space to permit the vertical indexing structure to fit between the subject magazine and a magazine on the other side of the vertical indexing structure. In the past, a series of motions implemented by more than one motor were required in order to establish the requisite space next to the subject magazine. It would be advantageous to be able to establish the desired space next to the subject magazine by implementing only a single motor.
There existed a need to provide an apparatus and method, implementing only a single motor, to laterally index a line of magazines holding molded leadframes, one at a time, to an operating position along the line. Additionally, the lateral indexing of the magazines establishes enough space adjacent to a magazine in the operating position in order to permit a vertical indexing structure to fit next to this magazine. The vertical indexing structure moves the stack of molded leadframes in the magazine at the operating position up or down as required to keep the pick up or drop off position constant for a molded leadframe handling apparatus operating on the stack.